Energy savings and reduction of CO2 emission using Ca(OH)2 incorporated zeolite as an additive for warm and hot mix asphalt production

WMA (Warm-mix asphalt) has been gaining popularity primarily because of its lower energy consumption and reduced air emissions. This study investigated the energy saving and CO2 emission reduction properties of Ca(OH)2 incorporated zeolite (CaZ), synthesized by a sol-gel method and used as an additive for ASCON (asphalt concrete) production at different temperatures (120, 140 and 180 °C). The addition of up to 6 wt.% CaZ lowered the ASCON production temperature to 120 °C, leading to a production cost saving of 0.882 million US$/y, and an energy saving of 24,831 GJ/y for 140,000 Tonne/y compared to conventional HMA (hot mix asphalt) production at 180 °C. In addition, CO2 emission was reduced from 7500 ppm for HMA production to 500 ppm for WMA production at 120 °C. The significantly lower energy consumption and CO2 emission resulting from addition of CaZ composite are associated with easy release of water vapor due to the dendrite nano structure of the synthesized CaZ, accompanied by easy volume expansion and asphalt viscosity reduction.